One known way for detecting optical radiation is by means of optical detectors that convert a photon into an electron via electron/hole generation upon impact of a photon in a generation/recombination zone. The sum of the electrons/holes generated by the photons represents a signal current that corresponds to the received optical power. This is equivalent to the number of photons incident to the detector that are actually converted to electrons. The conversion is typically done in a photo diode.
Thanks to the particle <-> wave duality of light, the light can be interpreted as an electromagnetic wave rather than as a transmitted photon. The frequency of this electromagnetic wave is in the order of hundreds of THz for visible and infrared light emissions and tens of THz for far infrared light. Treating light as electromagnetic wave leads to approaches that use an antenna for reception of this electromagnetic wave. The problem of such an approach is to provide suitable solutions that can convert the extremely high-frequency wave as received by the antenna into a signal which can be handled by electronic devices capable of dealing with such high frequencies.
One way of doing this is by using very advanced diode topologies. Such a diode topology is e.g. known from “INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY, Nanotechnology 16 (2005), Optical antennas for nano-photonic applications, Javier Alda, José M Rico-Garce,´ýa, José M L´opez-Alonso and G Boreman”.
Another way of converting the antenna signal to a lower frequency signal is by using a bolometer. One known type of bolometer consists basically of a radiation-sensitive resistance element in one branch of a Wheatstone bridge. The term ‘radiation-sensitive’ means that the element can absorb incident electromagnetic energy (light waves). Changes of the absorbed electromagnetic energy cause changes in the electrical resistance of the radiation-sensitive-resistance element. The radiation-sensitive resistance element may be e.g. a platinum strip, a semiconductor film, or any other substance whose resistance is altered by slight changes in the amount of radiant energy falling on it.
It is an object of the invention to provide improved solutions for the detection of electromagnetic waves. It is a further object of the invention to provide improved solutions for detecting thermal radiation.